Lipids 1
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Questions and Answers

What is the main role of glycolipids in the cell membrane?

  • Contain phosphate groups for stability
  • Maintain stability and facilitate cellular recognition (correct)
  • Facilitate the spread of infection
  • Dissolve cell membranes

    • Which enzymes are produced by pathogenic bacteria to dissolve cell membranes?

  • Sphingomyelinases
  • Carbonyl reductases
  • Cholesterol esterases
  • Phospholipases (correct)

    • Which molecule is a component of glycosphingolipids but not phospholipids?

  • Phosphate
  • Fatty acid
  • Sphingosine
  • Ceramide (correct)

    • What is attached to the amino alcohol sphingosine in glycosphingolipids?

    <p>Fatty acid unit</p> Signup and view all the answers

    Which of the following is NOT a subclass of glycolipids?

    <p>Phosphatidylcholine</p> Signup and view all the answers

    What is the main outcome of attaching different polar head groups to diacylglycerol?

    <p>Degradation by phospholipases</p> Signup and view all the answers

    What type of molecule is a phospholipid?

    <p>Amphipathic</p> Signup and view all the answers

    Which of the following is a molecule with high physiological and metabolic relevance?

    <p>Diacylglycerol</p> Signup and view all the answers

    Which lipid serves as the building blocks of other lipids?

    <p>Glycerophospholipids</p> Signup and view all the answers

    What type of fatty acids are SFA and UFA?

    <p>Saturated and unsaturated</p> Signup and view all the answers

    Which category includes prostaglandins, thromboxanes, and leukotrienes?

    <p>Eicosanoids</p> Signup and view all the answers

    What is the precursor for all classes of steroid hormones?

    <p>Cholesterol</p> Signup and view all the answers

    Why do steroid hormones need to be attached to plasma proteins for transportation in the blood?

    <p>Due to hydrophobicity</p> Signup and view all the answers

    Which lipoprotein functions to keep its component lipids soluble for transport in plasma?

    <p>High-density lipoproteins (HDL)</p> Signup and view all the answers

    Where do abnormalities in lipoprotein metabolism generally occur?

    <p>At the site of lipid utilization</p> Signup and view all the answers

    Which type of lipoprotein has the highest density?

    <p>High-density lipoproteins (HDL)</p> Signup and view all the answers

    What is the function of plasma lipoproteins?

    <p>To provide a mechanism for lipid transport in plasma</p> Signup and view all the answers

    What is the main source of essential fatty acids that must be obtained from the diet?

    <p>Fish oils</p> Signup and view all the answers

    Which fatty acid is the precursor of arachidonic acid, which is important for eicosanoid synthesis?

    <p>Linoleic acid</p> Signup and view all the answers

    In phospholipids, what type of group links the polar head and nonpolar fatty acid tails?

    <p>Phosphate group</p> Signup and view all the answers

    Why are phospholipids considered amphipathic in nature?

    <p>They have both hydrophilic and hydrophobic components</p> Signup and view all the answers

    Which part of a phospholipid molecule points outward to the aqueous environment in cell membranes?

    <p>Hydrophilic head</p> Signup and view all the answers

    Apart from being main components of cell membranes, where else can nonmembrane phospholipids be found?

    <p>In lung surfactants</p> Signup and view all the answers

    What is the physiological relevance of cardiolipin?

    <p>Maintenance of electron transport chain complexes</p> Signup and view all the answers

    Which function is NOT associated with platelet-activating factor (PAF)?

    <p>Enhances erythrocyte production</p> Signup and view all the answers

    Where does the synthesis of glycerophospholipids primarily occur?

    <p>Smooth Endoplasmic Reticulum (sER)</p> Signup and view all the answers

    Which process results in the conversion of phosphatidic acid to diacylglycerol?

    <p>Phosphatase action</p> Signup and view all the answers

    In phospholipid biosynthesis, what is the precursor molecule for glycerophospholipids?

    <p>Fatty acyl CoA</p> Signup and view all the answers

    Which organelle is responsible for modifying newly synthesized phospholipids before they compose cell membranes?

    <p>Golgi Apparatus</p> Signup and view all the answers

    What type of fatty acids are the building blocks of lipids?

    <p>Saturated and unsaturated fatty acids</p> Signup and view all the answers

    Which lipid molecule is a combination of a fatty acid with an alcohol such as glycerol?

    <p>Neutral fats</p> Signup and view all the answers

    In glycerophospholipids, what is the primary role of the glycerol backbone?

    <p>Linking the polar head to the nonpolar fatty acid tails</p> Signup and view all the answers

    What is the main function of triacylglycerols (TAG) in cells?

    <p>Provide energy during fasting periods</p> Signup and view all the answers

    In what form are fatty acids mainly circulating in the blood plasma?

    <p>Esterified forms within lipoprotein particles</p> Signup and view all the answers

    Why do long-chain-length fatty acids (LCFA) require association with proteins for blood plasma circulation?

    <p>To increase their solubility in water</p> Signup and view all the answers

    What effect does the presence of double bonds have on the melting temperature (Tm) of fatty acids?

    <p>Decreases the Tm</p> Signup and view all the answers

    Which aspect of fatty acid structure gives them an amphipathic nature?

    <p>Anionic group</p> Signup and view all the answers

    What structural characteristic defines saturated fatty acids?

    <p>Absence of double bonds</p> Signup and view all the answers

    What is the main function of cholesteryl esters (CE) in the body?

    <p>Modulate the fluidity of lipoproteins</p> Signup and view all the answers

    Why are cholesteryl esters (CE) not found in cell membranes?

    <p>They are only present in low levels associated with lipoproteins</p> Signup and view all the answers

    What role does the liver play in cholesterol homeostasis in the body?

    <p>It controls the delicate balance of cholesterol levels in the body</p> Signup and view all the answers

    How does cholesterol contribute to the formation of dangerous plaque formations?

    <p>Due to disturbances in the balance controlled by the liver</p> Signup and view all the answers

    Which statement accurately describes cholesterol's role as a sterol?

    <p>Cholesterol acts as a precursor for eicosanoid synthesis</p> Signup and view all the answers

    In what form do most plasma cholesterol exist for transport?

    <p>Cholesteryl esters with fatty acids attached</p> Signup and view all the answers

    What is the role of cardiolipin in the cell?

    <p>Maintains electron transport chain complexes</p> Signup and view all the answers

    Where does the synthesis of glycerophospholipids primarily occur?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What is the function of platelet-activating factor (PAF) in the body?

    <p>Activates inflammatory cells</p> Signup and view all the answers

    What role does the smooth endoplasmic reticulum (sER) play in phospholipid synthesis?

    <p>Produces phospholipids from precursors</p> Signup and view all the answers

    What is the precursor molecule for glycerophospholipids in phospholipid biosynthesis?

    <p>Fatty acyl CoA</p> Signup and view all the answers

    Which organelle is responsible for modifying newly synthesized phospholipids before they become part of cell membranes?

    <p>Golgi apparatus</p> Signup and view all the answers

    Why must steroid hormones be attached to plasma proteins for transportation in the blood?

    <p>To enhance their solubility due to their hydrophobic nature</p> Signup and view all the answers

    Which lipoprotein has the highest density among the listed types?

    <p>High-density lipoproteins (HDL)</p> Signup and view all the answers

    Where do abnormalities in lipoprotein metabolism generally occur?

    <p>At the site of lipoprotein production</p> Signup and view all the answers

    What is the main function of plasma lipoproteins?

    <p>To keep their component lipids soluble for transport in plasma</p> Signup and view all the answers

    In what way do chylomicrons, VLDL, LDL, and HDL differ from each other?

    <p>Lipid and protein composition, size, density, and site of origin</p> Signup and view all the answers

    What is the precursor for all classes of steroid hormones?

    <p>Cholesterol</p> Signup and view all the answers

    What is the main component of lecithin?

    <p>Phosphatidylcholine</p> Signup and view all the answers

    Which type of phospholipid is an important component of the myelin sheath of nerve fibers?

    <p>Sphingomyelin</p> Signup and view all the answers

    What is the precursor molecule of phosphatidylinositol?

    <p>Inositol</p> Signup and view all the answers

    Which alcohol group is involved in the synthesis of Phosphatidylethanolamine?

    <p>Ethanolamine</p> Signup and view all the answers

    What is the main outcome of attaching serine to phosphatidic acid?

    <p>Formation of Phosphatidylserine</p> Signup and view all the answers

    Which phospholipid is essential for regulating intracellular signaling, lipid transportation, and vesicular trafficking?

    <p>Phosphatidylinositol</p> Signup and view all the answers

    What is the physiological relevance of cardiolipin in the cell?

    <p>Maintains electron transport chain complexes</p> Signup and view all the answers

    Where does the synthesis of phospholipids primarily occur?

    <p>Smooth endoplasmic reticulum (sER)</p> Signup and view all the answers

    Which organelle is responsible for modifying newly synthesized phospholipids before they become part of cell membranes?

    <p>Golgi apparatus</p> Signup and view all the answers

    What is the precursor molecule for glycerophospholipids in phospholipid biosynthesis?

    <p>Glycerol-3-phosphate</p> Signup and view all the answers

    What is the primary role of platelet-activating factor (PAF) in the body?

    <p>Induces hypersensitivity reactions</p> Signup and view all the answers

    How are glycerophospholipids synthesized?

    <p>$2$ fatty acids linked to coenzyme A are joined to glycerol-3-phosphate.</p> Signup and view all the answers

    What is the term used to describe fatty acids with 13-21 carbons?

    <p>Long-chain fatty acids (LCFA)</p> Signup and view all the answers

    Which carbon atom in a fatty acid is referred to as the α-carbon?

    <p>Carbon 2</p> Signup and view all the answers

    What is the reference point used to name double bonds in a fatty acid?

    <p>ω-carbon</p> Signup and view all the answers

    Arachidonic acid is categorized as an ω-6 fatty acid because:

    <p>The first double bond is six carbons from the ω end</p> Signup and view all the answers

    What is the term used to describe fatty acids with fewer than 5 carbons?

    <p>Short-chain fatty acids (SCFA)</p> Signup and view all the answers

    What is the function of glycosphingolipids located in the outer parts of the plasma membrane?

    <p>Antigenic/recognition function</p> Signup and view all the answers

    Which blood group antigen is associated with the presence of GalNAc as the terminal sugar on the glycan?

    <p>A</p> Signup and view all the answers

    What is the main source of arachidonic acid, the immediate precursor of eicosanoids?

    <p>Membrane phospholipids</p> Signup and view all the answers

    Which lipid derivatives are classified as local hormones due to their acting locally and not being stored?

    <p>Prostaglandins, thromboxanes, and leukotrienes</p> Signup and view all the answers

    Which lipid molecule serves as a mediator of allergic response and inflammation?

    <p>Leukotrienes</p> Signup and view all the answers

    What is the essential characteristic that distinguishes arachidonic acid from essential fatty acids?

    <p>Not stored in tissues</p> Signup and view all the answers

    What is the structure of cholesterol consisting of?

    <p>Four fused hydrocarbon rings</p> Signup and view all the answers

    Where are cholesteryl esters (CE) primarily found in the body?

    <p>Associated with lipoproteins</p> Signup and view all the answers

    Which molecule is an essential precursor for the synthesis of steroid hormones?

    <p>Cholesterol</p> Signup and view all the answers

    What is the primary source of cholesterol entry into the liver for maintaining homeostasis?

    <p>Dietary intake and de novo synthesis</p> Signup and view all the answers

    What crucial function does cholesterol perform in cell membranes?

    <p>Enhancing membrane fluidity</p> Signup and view all the answers

    In what form is most plasma cholesterol found for transport?

    <p>Cholesterol esterified with fatty acids</p> Signup and view all the answers

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